Abstract
The inactivation method which combined freezing treatment with high-pressure treatment was examined using the coliform groups which is the index of food contamination. Especially this study estimated the influence of salt, sucrose, and pH for the inactivation of Escherichia coli, Citrobacter freundii, Enterobacter aerogenes, Enterobacter cloacae and Klebsiella pneumoniae of coliform groups. When pressure and freezing treatment was performed for any solution of coliform groups which prepared salt concentration, the inactivation effect increased in the solution of Escherichia coli and Citrobacter freundii. However, there was almost no influence of salt concentration in Enterobacter aerogenes, Enterobacter cloacae and Klebsiella pneumoniae. On the other hand, in the case of the solution containing sucrose, the inactivation effect fell in the solution of Escherichia coli and Citrobacter freundii, but there was no influence of sucrose concentration in Enterobacter aerogenes, Enterobacter cloacae and Klebsiella pneumoniae. Furthermore, in the case of the solution prepared to pH 4.3-8.0, the inactivation effect was the highest in all solution of coliform groups at pH 4.3. Moreover, in order to evaluate the inactivation effect to food, the herring roe was used and pressure and freezing treatment was performed. When the herring roe which carried out packing after dipping in any solution of coliform groups was processed, pressure and freezing treatment showed the effective inactivation effect as compared with freezing treatment.
